Please check my answers:

4) Professional Dental Supply has been successfully selling dental instruments to dentists for the past 20 years, and has developed strong customer relations. When looking for new marketing opportunities, Professional Dental Supply will most likely look first at
A.

Market development.
B.

Market penetration.
*C.*

Product development.
D.

Diversification.

5) Which of the following statements regarding marketing strategies is FALSE?
A.

Developing successful marketing strategies does not need to be a hit-or-miss proposition.
B.

It is useful to think of the marketing strategy planning process as a narrowing-down process.
C.

These strategies require decisions about the specific customers the firm will target and the marketing mix the firm will develop to appeal to that target market.
*D.*

These strategies must meet the needs of target customers, and a firm is likely to get a competitive advantage if it just meets needs in the same way as some other firm.

6) To compete more successfully with its many competitors offering packaged cookies, Famous Amos added its own line of extra chunky premium cookies. This seems to be an effort at:
A.

Market development.
B.

Combination.
C.

Product development.
*D.*

Market penetration.

Those look right to me.

Looks right to me

#4 is product development

The four Ps of a marketing mix are:

Your answers are correct! Here's an explanation of each question:

4) Professional Dental Supply has been successfully selling dental instruments to dentists for the past 20 years, and has developed strong customer relations. When looking for new marketing opportunities, Professional Dental Supply will most likely look first at:
The correct answer is C. Product development.
Professional Dental Supply has already established a strong customer base and has been successful in selling dental instruments. To continue growing and expanding their business, they would most likely focus on developing new products or improving existing ones to meet the needs and preferences of their current customers. This strategy is known as product development.

5) Which of the following statements regarding marketing strategies is FALSE?
The correct answer is D. These strategies must meet the needs of target customers, and a firm is likely to get a competitive advantage if it just meets needs in the same way as some other firm.
This statement is false because meeting the needs of target customers alone is not enough to gain a competitive advantage. In order to stand out from competitors, a firm must find unique ways to meet those needs or provide additional value beyond what other firms are offering. Simply meeting needs in the same way as other firms may not differentiate a company and may result in intense competition based on price or other factors.

6) To compete more successfully with its many competitors offering packaged cookies, Famous Amos added its own line of extra chunky premium cookies. This seems to be an effort at:
The correct answer is C. Market penetration.
Famous Amos adding its own line of extra chunky premium cookies is an example of product development. This strategy aims to capture more market share by introducing new or improved products to the existing market. By offering premium cookies with a unique selling proposition of being extra chunky, Famous Amos is attempting to penetrate the market further and attract more customers away from its competitors.