The old woman _____ I talked just now is my grandma

选A。这是一个定语从句，首先，the old woman是先行词，所以关系代词应该用that/who/whom，其次，关系代词需在后面的定语从句中充当成分，talk是不及物动词，所以原句应该是：The old woman that/who/whom I talked to just now is my grandma.而选项中to 放在了关系代词的前面，所以只能选A 。