 <translate> 7a/30 tells us that a is a factor of 30, which has 2, 3, and 5 as its prime factors. Each of them is distinct. Moreover, all multiples of 30 less than 200 can be derived by multiplying these prime factors alone. Thus, number of different prime factors is 3.
Thus, the answer is (B). <yor> 7a/30 sọ fún wa pé a jẹ́ kókó 30, èyí tí ó ní 2, 3, àti 5 gẹ́gẹ́ bí àwọn kókó pàtàkì rẹ̀. Gbogbo wọn ló yàtọ̀ síra. Yàtọ̀ síyẹn, gbogbo ìlọ́po ọgbọ̀n tí kò tó igba ni a lè rí nípa gbígbé àwọn kókó pàtàkì wọ̀nyí pọ̀. Nítorí náà, iye àwọn onímọ̀-ọ̀rọ̀ pàtàkì tó yàtọ̀ síra jẹ́ 3. Nítorí náà, ìdáhùn náà ni (B). 