Consider the following statements in connection with involute profile characteristics:
1. Tangent to base circle is also tangent to profile
2. Common tangent to two base circle passes through pitch point
3. Pressure angle for involute profile is constant
4. Involute teeth gear correctly even when centre distance is varied slightly
Which of these statements are correct?
(a) 1, 2 and 3 only (b) 1, 3 and 4 only
(c) 2, 3 and 4 only (d) 1, 2, 3 and 4