Choose the grammatically correct sentence.

A. Está cosa es un lápiz amarillo.<<X
B. Esta cosa es un lápiz amarillo.
C. Esta cosa es una lápiz amarilla.
D. Esta cosa es unas lápiz amarilla. <<X

Not sure between B or C un or una ??

B. 'amarillo' and 'un' modify el lápiz, not la cosa.

If you don't understand why it is B, ask.

Sra

The grammatically correct sentence is option B: "Esta cosa es un lápiz amarillo."

To determine whether to use "un" or "una" in this sentence, we need to consider the gender of the noun "lápiz" (pencil). In Spanish, "lápiz" is masculine, so we should use the article "un" before it.

Therefore, the correct sentence is: "Esta cosa es un lápiz amarillo." This translates to "This thing is a yellow pencil."