Consider the following statements in respect of investment castings:
1. The pattern or patterns is/are not joined to a stalk or spure also of wax to form a tree of patterns
2. The prepared moulds are placed in an oven and heated gently to off the invest and melt out of the bulk of wax
3. The moulds are usually poured by placing the moulds in a vacuum chamber
Which of these statements are correct?
(a) 1 and 2 only (b) 1 and 3 only
(c) 2 and 3 only (d) 1,2 and 3