In the following passage, some words have been deleted. Select the most appropriate option to fill in each blank.

(1) ______ changes in science and technology lead to modernisation of technology as well as upgradation of knowledge. In order to upgrade or modernise technology, management must (2) ______ employees to accept new technology. (3) ______ training of staff becomes necessary to update their knowledge and to (4) ______ their skills. This is possible only (5) ______ effective communication between the management and the employees

Select the most appropriate option to fill in blank number 4.