What is the main difference between haploid and diploid cells?

A Haploid cells have the same number of chromosomes as diploid cells.
B Diploid cells have half the number of chromosomes as haploid cells.
C Diploid cells have the same number of chromosomes as haploid cells.
D Haploid cells have half the number of chromosomes as diploid cells.

D Haploid cells have half the number of chromosomes as diploid cells.