Question

Primary growth or lengthening of plants results from mitotic division in cells of which tissue? Axillary buds Lateral meristem Apical meristem

Answer 1

Plants have meristematic tissue in many locations. Both roots and shoots have meristematic tissue at their tips called apical meristems, which are responsible for the lengthening of roots and shoots.
The answer to the question above then is "apical meristem".