GMAT Club Official Solution:On Sunday, a farmer brought two types of fruit to the market: apples and pears. During the day, the farmer sold 1/7 of the apples he had brought. If the farmer sold at least 1 apple and at least 1 pear that day, did the farmer bring more than 105 pieces of fruit to the market? Firstly, note that on Sunday, the farmer sold 1/7 of the apples he had brought, so (apples brought on Sunday) = 7 * (apples sold on Sunday).
(1) The number of apples the farmer sold that day was 15/16 as many as the number of apples he sold on Saturday.
This implies that:
(apples sold on Sunday) = 15/16 * (apples sold on Saturday);
(apples sold on Sunday) / (apples sold on Saturday) = 15/16.
Hence, (apples sold on Sunday) must be a multiple of 15.
Since (apples brought on Sunday) = 7 * (apples sold on Sunday), (apples brought on Sunday) must be a multiple of 7 * 15 = 105. Therefore, the total number of fruit he brought (apples + pears) must be at least 105 + 1 = 106 (since he sold at least 1 pear then he must have brought at least 1 pear). Sufficient.
(2) During the day, the number of apples the farmer sold was 6/7 as many as the number of pears he sold.
This implies that:
(apples sold on Sunday) = 6/7 * (pears sold on Sunday);
(apples sold on Sunday) / (pears sold on Sunday) = 6/7.
Hence, (apples sold on Sunday) must be a multiple of 6. Since (apples brought on Sunday) = 7 * (apples sold on Sunday), (apples brought on Sunday) must be a multiple of 7 * 6 = 42.
If the farmer sold 6 apples and 7 pears, then he brought 7 * 6 = 42 apples and could have brought 7 pears, for a total of 49 pieces of fruit (not more than 105).
However, if the farmer sold 18 apples and 21 pears, then he brought 7 * 18 = 126 apples and must have brought at least 21 pears, for a total of at least 147 pieces of fruit (more than 105). Not sufficient.
Answer: A.