Question

we get oil from the ____ of mustard plant

Answer 1

leaf of the mustard plant

Answer 2

We get mustard oil from the seeds of mustard plant.  

Explanation:

Mustard plant is a 'plant species' of Brassicaceae family which is widely used to make spices, oil and its 'leaves' can be eaten as "mustard greens".

We can make mustard sauce by grinding and mixing its seed with vinegar, water and other liquid. It is a yellow condiment known as prepared mustard. The seeds are 'pressed' to extract 'mustard oil' from them.